Question I have 48gb RAM but system only sees 23.9 GB? B450M DS3H motherboard

[Jake Maverick]

This is a weird one that I can't figure out. RAM is seen in the BIOS as well as by windows 10, but only 23.9GB is available? I don't have an option in BIOS to set to 'Dual Channel' as some of the other threads suggest.... What can I do apart from swapping the sticks about on the board to see if that solves it? Bit awkward to get to....

Thanks in advance!

 

[SkyNetRising]

What can I do apart from swapping the sticks about on the board to see if that solves it?

Can you show screenshots from CPU-Z - memory and spd sections?
https://www.cpuid.com/softwares/cpu-z.html
(upload to imgur.com and post link)

What ram slots did you place ram modules in?
With 2 ram modules configuration they should be placed in slots A2 and B2 (2nd and 4th counting from cpu).

 

[geofelt]

What are the specs of your system.
Particularly make/model of the, ram and processor.

Is the 23.9gb available from a task manager display?
What that really means is that 23.9gb is instantly available, and the remainder is ram that is currently in use or allocated.
Not a problem.

48gb is a unusual size.
Is it all in one kit, and is it supported by the motherboard ram QVL list.

 

[35below0]

I don't have an option in BIOS to set to 'Dual Channel' as some of the other threads suggest.

Dual channel requires two or four identical sticks of RAM. Do you have one or three?

RAM Model? Please post the exact kit model.
- Open command prompt (hit winkey, search for "cmd").
- Type in or paste this: "wmic memorychip get devicelocator, partnumber"
Post the partnumber here.

 

[Jake Maverick]

Seems I have 16gb in slot one and two and 8gbs in three and four, I know rookie mistake...but that should not do it?
Just looked at imgur.com, not happy about putting phone number on internet.....any other option?

They must all be compatible? As they are seen by the motherboard. it was 2 x 8GB before, I upgraded with 2 x 16GB. In several s/w proggies it does 48gb seen but only 29.5GB is available....

Ryzen 5 machine.

DIMM 0 CMK32GX4M2A2666C16
DIMM 1 CMK16GX4M2D3000C16
DIMM 0 CMK32GX4M2A2666C16
DIMM 1 CMK16GX4M2D3000C16

 

[Jake Maverick]

if one of the 16GBs is faulty, surely it would read as 32GB available?

 

[35below0]

With mixed kits you never know what will happen. Maybe it works, maybe PC doesn't boot.

Unfortunately, your best bet would be to sell your two kits and buy one 2x32 or 2x24 kit. That would run fastest (because memory controlers do not like the extra work involved in running 4 sticks, they slow RAM down).

Edit - if two kits are compatible that still doesn't mean they will like working with each other. For best results always use one single kit. 2 or 4 sticks, 2 being prefered.

 

[geofelt]

Ram to operate properly must be all from the same matched kit.
Even the same part numbers may not work together, the internal chips may be entirely different.

Ryzen is particularly sensitive to ram compatibility issues.
Run memtest86+
It boots from a usb stick and does not use windows.
You can download it here:

Memtest86+ | The Open-Source Memory Testing Tool

Memtest86+ is an advanced, free, open-source, stand-alone memory tester for 32- and 64-bit computers (UEFI & BIOS supported)

memtest.org

See if there is a bios update for your motherboard that addresses ram compatibility issues.

If you can run a full pass with NO errors, your ram should be ok.

Running several more passes will sometimes uncover an issue, but it takes more time.
Probably not worth it unless you really suspect a ram issue.

If you run clean, your problem is likely elsewhere.
Sometimes increasing the ram voltage will get things to work.
XMP or the ryzen equivalent is not likely to work.
The specs embedded in the ram may well be different.

 

[Jake Maverick]

ok folks, thanks for all your help! Really tight budget here so I can't buy optimally, have to grab stuff when i see it about to go for good price.....I will try what you have suggested and hopefully get back to you tomorrow....

 

[35below0]

ok folks, thanks for all your help! Really tight budget here so I can't buy optimally, have to grab stuff when i see it about to go for good price.....I will try what you have suggested and hopefully get back to you tomorrow....

If you run just the 32Gb kit, is everything ok? Can you run it at 2666Mhz?

Your problems may be due to mixing kits, so keeping the larger of the two could solve problems.
You have the option of selling the smaller one. Not ideal, but you know...

 

[Bob.B]

Seems I have 16gb in slot one and two and 8gbs in three and four, I know rookie mistake...but that should not do it?
Just looked at imgur.com, not happy about putting phone number on internet.....any other option?

They must all be compatible? As they are seen by the motherboard. it was 2 x 8GB before, I upgraded with 2 x 16GB. In several s/w proggies it does 48gb seen but only 29.5GB is available....

Ryzen 5 machine.

DIMM 0 CMK32GX4M2A2666C16
DIMM 1 CMK16GX4M2D3000C16
DIMM 0 CMK32GX4M2A2666C16
DIMM 1 CMK16GX4M2D3000C16

Remove the 2x8 sticks and install the 2x16 sticks in a2+b2....test.

 

[SkyNetRising]

Just looked at imgur.com, not happy about putting phone number on internet.....any other option?

There's no need to register, to upload images.
At imgur.com web site click on upper left corner <new post>.

With CPU-Z screenshots show also
screenshot from task manager - Performance/Memory section.